This application claims the priority benefit of Japanese Patent Application No. 2001-001966, filed on Jan. 9, 2001, and entitled xe2x80x9cSlider, Head Assembly, and Disk drive Unit.xe2x80x9d
1. Technical Field
The present invention relates to a slider provided with a head for reading/writing data from/on a magnetic disk, more particularly to a technique that can reduce deposition of particles on the slider.
2. Description of the Related Art
A hard disk drive (HDD), which is the most popular recording means of computers, is structured so as to drive a single or a plurality of magnetic disks disposed at the same rotation axis with use of a spindle motor. A head disposed so as to face a magnetic disk is used to read/write data on/from the magnetic disk. This head is driven by an actuator, generally referred to as a voice coil motor (hereafter, to be described as the VCM). The magnetic disk, the head, and the actuator are all housed in an enclosure referred to as a disk enclosure. Such a disk enclosure is configured by a thin box like base, for example, an aluminum alloy base and a top cover for sealing the opening of the base.
Some of such heads used to read/write data have a transducer for writing data and magnetizing means for reading data separately. The magnetizing means for reading is realized actually by, for example, the magneto resistive (MR) effect or the giant magneto resistive (GMR) effect. The magnetizing means for reading, which employs the MR or GMR, is affected less by noise, thereby it can improve the recording density of disks. A head is disposed at a predetermined position of a member referred to as a slider. A slider includes a head sometimes. Sometimes the slider means the head simply. Concretely, sometimes the head and the slider are recognized to be equivalent to each other.
When such a head reads/writes data from/on a magnetic disk, the head (slider) flies above the magnetic disk at a predetermined height. This flight of the head above the magnetic disk is caused by the air bearing induced on the magnetic disk by the rotation of the magnetic disk. This is why the surface of the slider, which faces the magnetic disk, is referred to as an air bearing surface (hereinafter, to be described as the ABS). The property of this ABS affects the flight of the slider significantly.
The flying height of the slider from the magnetic disk should therefore be as low as possible when much consideration is given to reading/writing of data. This is because the mutual magnetic action between the magnetic disk and the head must be secured enough. Consequently, a slider that flies low should be employed for higher density magnetic recording. An excessively low flying height will cause the head to come in contact with fine projections formed on the surface of the magnetic disk, however. It is therefore indispensably important to smooth the surface of the magnetic disk so as to realize high density magnetic recording.
There is a conventional disk drive unit in which the slider is enabled to rest in a retreat area formed on a magnetic disk while the magnetic disk does not rotate and the slider flies from the retreat area when the magnetic disk begins rotating so as move (seek) to a data recorded area of the magnetic disk. This disk drive unit is referred to as a contact start and stop (CSS) type disk drive unit. On the contrary, there is also a loading/unloading type disk drive unit in which the slider is retreated to a ramp formed outside a magnetic disk while the magnetic disk does not rotate.
3. Problems to be Solved by the Invention
The main technical issues of the HDD are improvement of the recording capacity per magnetic disk and faster reading/writing data from/on the magnetic disk. Faster reading/writing data from a magnetic disk can be realized by reducing the seek time with which the magnetic head moves to a target track on the magnetic disk. Because the head is driven by a VCM as described above, the VCM performance is improved so as to improve the seek time. And, in order to improve the VCM, it is just required to employ a permanent magnet of the VCM, having a stronger magnetic property or increasing the thickness of the permanent magnet so as to increase the magnetic field to be applied to the voice coil of the VCM.
Reading/writing of data can also be made faster by increasing the rotation speed of the magnetic disk. In this case, however, faster rotation of the magnetic disk causes particles to hit the slider (head) more often when the number of particles in the subject HDD is the same as that when the rotation of the magnetic disk is slow. Particles mean powder existing in the HDD. Collision of those particles against the surface of the magnetic disk often causes hardware errors, that is errors in reading/writing of data, resulting in a loss of reliability in the HDD. On the other hand, because the flying height of the slider (head) from the magnetic disk has been required to be reduced so as to cope with the higher capacities of magnetic disks, the peril of collision of even fine particles that have been neglected against the slider (head) has also risen more and more.
Under such circumstances, it is an object of the present invention to provide a slider and a disk drive unit that can reduce read/write errors caused by particles, as well as assure reliability.
In order to achieve the above object, the present inventor observed actions of particles against a slider. As a result, the inventor recognized that the number of read/write errors was varied among the shapes of the ABS on a kind of a slider and there occurred a difference among the particles deposition states according to the ABS shape. Concretely, when the number of deposited particles is reduced, it is also possible to reduce the number of data read/write errors.
More concretely, the present invention provides a slider disposed so as to face a disk-like recording medium and enabled to support a head for reading/writing data from/on the disk. The slider comprises a slider body provided with an air leading edge, an air trailing edge, and an air bearing surface formed between the leading edge and the trailing edge; a rail formed almost like a U-letter on the air bearing surface so that its tip is disposed at the trailing edge side; and a pair of landing pads formed between the tip of the rail and the trailing edge. One of the pair of landing pads is curved convexly at its side facing the rail of the landing pad which is disposed at the outer periphery side of the disk-like recording medium while the slider is disposed so as to face the medium.
The slider of the present invention has the landing pads. And, the present inventor et al recognized through the examinations as described above that particles were apt to deposit at one side of a landing pad, which faces the rail. Especially, particles are apt to deposit on one of the pair of landing pads, which is disposed at the outer periphery side of the disk-like recording medium while the slider is disposed so as to face the medium. Thus, the inventor et al changed the shape of the landing pad and knew that the amount of deposited particles was varied among the shapes of the landing pad. Concretely, when the side of a landing pad, which faces the rail, is curved convexly, the deposition of particles can be reduced. This is why the slider of the present invention has been proposed. In the case of the present invention, the leading edge is disposed at the upstream of the trailing edge in the rotational direction of the disk-like recording medium.
Each landing pad of the slider of the present invention can be curved convexly in the center of the width direction. As to be described later, this is because deposition of particles on the landing pad can be reduced more significantly when the center portion in the width direction is curved convexly such way.
Furthermore, in the case of the slider of the present invention, a pad for applying a positive pressure to the slider can be formed on the rail, at the leading edge side, and between the pair of landing pads. When a surface that generates a negative pressure is formed in an area enclosed by the rail, the slider of the present invention functions as a negative pressure slider and it flies above the magnetic disk at a slower rotation speed. In addition, the slider can suppress the variation of the flying height in the radial direction of the disk-like recording medium.
Furthermore, the present invention provides a head assembly configured by a slider disposed so as to face a disk-like recording medium and enabled to support a head for reading/writing data from/on the medium and an actuator used to support and move the slider above the disk-like recording medium. The slider comprises a slider body provided with a leading edge and a trailing edge disposed at a predetermined interval therebetween in the rotational direction of the disk-like recording medium, an inner edge and an outer edge disposed at a predetermined interval therebetween in the radial direction of the disk-like recording medium, and an air bearing surface formed among the leading edge, the trailing edge, the inner edge, and the outer edge respectively; a cross rail formed along the leading edge; a pair of side rails extended from both ends of the cross rail to the trailing edge; a first pad formed between the cross rail and the boundary between the pair of side rails and enabled to apply a positive pressure to the slider; a pair of streamlined landing pads formed between the end of each of the side rails disposed at the trailing edge side and the trailing edge; a center rail formed between the pair of landing pads; and a second pad formed on the center rail and enabled to apply a positive pressure to the slider. Because the head assembly of the present invention has streamlined landing pads as described above, deposition of particles on those landing pads can be suppressed.
For the head assembly of the present invention, one of the pair of landing pads, which is disposed at the outer edge side, should preferably be streamlined to the air flow from the outer edge when the disk-like recording medium rotates. As to be described later, this is because particles are apt to deposit on one of the pair of landing pads, which is disposed at the outer edge side. In the case of the present invention, the inner edge means an edge disposed at the inner periphery of the disk-like recording medium while the slider is disposed so as to face the disk-like recording medium. The outer edge means an edge disposed at the outer periphery of the disk-like recording medium while the slider is disposed so as to face the disk-like recording medium.
In the head assembly of the present invention, each landing pad can have an inclined plane in the air flowing direction. It is a concrete example of the streamlined landing pad described above. When the landing pad is formed such way, the air flow cleans the inclined plane, thereby deposition of particles on the landing pad can be suppressed more effectively.
Furthermore, in the head assembly of the present invention, a negative pressure pocket can be formed in an area enclosed by the cross rail and the pair of side rails. The pocket applies a negative pressure to the slider when the disk-like recording medium rotates. Because of the combination of the first and second pads that apply a positive pressure to the slider respectively and the negative pressure pocket as described above, the slider of the present invention functions as a negative pressure slider, so that the slider can fly above the disk at a slower rotation speed. It is thus possible to suppress the variation of the flying height of the slider to occur in the radial direction of the disk-like recording medium.
Furthermore, the present invention provides a disk drive unit comprising a disk-like recording medium driven rotationally around a rotation axis and enabled to write data thereon; a slider provided with a head for reading/writing the data from/on the medium; an actuator for seeking the slider above the disk-like recording medium; and an enclosure for housing the disk-like recording medium, the slider, and the actuator. The slider comprises a slider body provided with an air leading edge, an air trailing edge, and an air bearing surface formed between the leading edge and the trailing edge; a rail formed almost like a U-letter on the air bearing surface so that its tip is disposed at the trailing edge side; and a pair of landing pads formed between the tip of the rail and the trailing edge. One of the pair of landing pads, which is disposed at the outer periphery side of the disk-like recording medium is provided with an inclined surface inclined in the width direction at its side facing the leading edge.
The disk drive unit of the present invention is provided with a pair of landing pads that configures the slider and one of the landing pads, which is disposed at the outer periphery side of the disk-like recording medium, is provided with an inclined plane inclined in the width direction at its side facing the leading edge. The air flow against the landing pad does not stagnate so much on such an inclined plane. In the case where the air flow stagnates, it causes particles to deposit more easily. The landing pad of the present invention, having such an inclined plane will therefore be effective for preventing the air flow from stagnation, thereby suppressing deposition of particles. After all, the present invention can reduce the number of hardware-caused errors, thereby improving the reliability of the disk drive unit.
In the disk drive unit of the present invention, the inclined plane may be varied freely in shape. Because the inclined plane of the present invention is formed so as to suppress deposition of particles on the landing pad, the inclined plane is formed just at a predetermined place of the subject landing pad at which such deposition of particles can be suppressed. Consequently, the inclined plane may be formed entirely or partly in the width direction of the landing pad. The inclined plane may be formed not only in a direction, but also in a plurality of directions. For example, the slider 3b shown in FIG. 3 (to be described later) has landing pads, each of which has an inclined plane inclined in one direction. The slider 3a shown in FIG. 1, however, has landing pads, each of which is inclined in a plurality of directions (actually, two directions).